Okla. Stat. tit. 68, § 804.1

For deaths occurring on or after January 1, 2010, no lien related to estate tax shall attach to any property passing through the estate of a decedent, by joint tenancy, or otherwise. No order exempting estate tax liability shall be necessary to authorize the release of such property or for the title of real property to be marketable. This shall not be construed as relieving an estate from lien obligations in effect for deaths occurring before January 1, 2010; provided, that for deaths occurring before January 1, 2010, any lien related to estate tax shall be extinguished subsequent to the lapse of ten (10) years after the date of death of a decedent and no order exempting estate tax liability shall be necessary to authorize release of such property or for the title of real property to be marketable.